Dental chair



(No Model.) 2 SheetsSheet 1.

ABRUSTLEQ DENTAL CHAIR.

No. 447,487. Patented Mar. 3 1891.

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(No Model.) 2 Sheets-Sheet 2.

LBRU STLE. DENTAL CHAIR.

No. 447,487. Patented Mar. 3, 1891.

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ANDREXV BRUSTLE, OF HYDE PARK, ASSIGNOR TO JOHN HOOD AND STEPHEN H.REYNOLDS, OF BOSTON, MASSACHUSETTS.

DENTAL CHAIR.

SPECIFICATION forming part of Letters Patent N 0. 447,487, dated March3, 1891.

I Application filed May 12, 1890. Serial llo. 351,406. (No model.)

To aZZ whom, it may concern:

Be it known that 1, ANDREW BRtisTLE, of Ilyde Park, in the county ofNorfolk and State of Massachusetts, have invented new and usefulImprovements in Dental Chairs, of which the following, taken inconnection with the accompanying drawings, is a specification.

This invention relates to improvements in dental chairs of that class inwhich the frame for supporting the seat, head, back, and foot rests ispivoted to the base in such a manner that it may be tilted to anydesired position and there securely locked.

The invention has for its object the construction of a device fortilting the frame of the chair, which shall be efficient in looking itin position, and which shall be simple in construction and easilyoperated and present a neat appearance.

The invention has further for its object the novel construction,arrangement, and combination of parts, as will be hereinafter fully setforth, pointed out in the claims hereto appended, and illustrated in theaccompanying d rawin gs.

In the accompanying drawings, in which similar letters of referencedesignate corresponding parts, Figure 1 is a side elevation of the baseof a chair embodying the invention, showing the chair in its normalposition. Fig. 2 is a similar view showing the chair tilted backward.Fig. 3 is a plan View. Fig. 4c is a detail view showing the frame forsecuring the segmental gears in their relative positions. Fig. 5 is anend elevation of one of the segmental gears with the frame attached.

Referring to the drawings by letter, A designates the base of the chair,provided with legs 13 B, on which it rests when in use. It is rotatablymounted on the pedestal O, and a cam O, operated by a lever C, isprovided, so that the chair-frame can be raised until its legs clear thefloor and then be rotated. The cam passes transversely through the base,having its ends journaled in the same and its fiat surface resting onthe top of the pedestal, so that when it is operated by the lever theframe will be raised. From the front of the base projects a sleeve D,forming a journal for the shaft D, which passes through it and has itsends projecting from both sides. The se mental gears E are keyed onthese projecting ends at their lower ends. base is pivoted thechair-frame, which has its side standards G extending below the pivotalpoint. Near the lower ends of these standards are pivoted at their lowerends the segmental gears E, which mesh with the gears E, secured to theshaft D, journaled in the base. In the present instance the gears areshown and described as segments of circles. By experiment, however, theinventor has found that a somewhat better result is ob-.

tained in the way of a smoother and more even movement by slightlycutting away the engaging surfaces ofthe upper part of the gear E andthe lower part of the gear E and slightly extending the engagingsurfaces of the upper part of the gear E and the lower part of thegearE. They are so nearly true segments, however, as stated before, thatthey are shown and described as such, as they will work very near aswell as the modified form just referred to. To retain the gears in theirrelative positions a frame is provided, which is journaled at its endson lugs M projecting from the center of the segments, one on each sideof each pair of gears. This frame consists of a collar J, journaled onthe bearings M, and has lugs K projecting from its opposite sides. Thesecollars are connected by rods L, each rod passing through a lug of eachcollar, and may be secured in place in any suitable manner. A foot-leverF for operating the gears is keyed on the shaft D and To the top of the.

extends backward, so as to be easily reached by the operator. The freeend of the lever is slotted and moves up and down on a curved rack F,secured to one of thelegs of the chair. To lock the lever on the rack aspring-catch F is provided.

If it is desired to tilt the chair backward from its normal position,the operator places his foot on the lever F, releases the catch, andallows the lever to gradually rise, the chair being moved by the hand,01' ordinarily it will move by itself, the weight being backof the pointwhere it is pivoted to the base. When it has reached the desiredposition, the catch is released and the lever locked on the rack,preventing any further movement of the gears, and thereby holding itfirmly in place. To raise the chair again to its normal position thelever is pressed upon by the foot, the catch disengaged, and the leverforced down, which causes a partial rotation of the gears. One of thegears being attached to a shaft journaled in the base and the other tothe frame at points near their peripheries, as the gears are turneddownward these points will be forced farther apart, and as the former isimmovable, being fast to the base, the lower end of the standard will heforced backward in consequence, and thereby bring the chairframe to itsnormal position.

Ilavin g thus described my invention, what I claim, and desire to secureby Letters Patent, is-

1. In a dental chair, the base, the side stand ards pivoted to the base,the segmental gears keyed on a shaft journaled to the base, thesegmental gears pivoted to the side standards and meshing with thesegmental gears pivoted to the base, and the lever for operating thesame, substantially as and for the purpose :5 specified.

2. In a dental chair, the base, the frame pivoted to the base, thesegmental gears pivoted to said frame and meshing with similar gearskeyed on a shaft journaled to the base, and the frame connecting theintermeshing o gears, substantially as and for the purpose specified.

8. In a dental chair, the combination of the base, the frame pivoted tothe base, the means for rotating said frame, consisting of the seg- 5mental gears keyed on a shaft journaled to the base and meshing withsimilar gears pivoted to the standards of the frame, the lever foroperating said gears, the curved rack, and the frames connecting thecenters of the seg- 4o mental gears for holding them in their relativepositions, substantially as and for the purpose specified.

In testimony whereof I have signed my name to this specification, in thepresence of two subscribing witnesses, on this 6th day of May, A. I).1890.

ANDREW BRUSTLE.

Witn esses:

PERRY M. BLAKE, GEORGE SANFORD.

